law feer law enforcement to say, keep an eye on this person, we think he may be up to no good? does that happen a lot, or is it rare? >> i'm not in a position to say how many times any specific government has communicated to the united states government, but it's fair to say that w whenever we get such communications i think we want to take them very seriously. >> in 2011 the fbi was informed by the russian fsb, the successor organization to the kgb, that they were concerned about the older brother. the fbi says they looked into his communications, they interviewed him, they didn't find there to be anything that would pose a threat to public safety, and then the older brother went to russia, we presume, to chechnya, came back. should the fbi re-interviewed him after he came back? >> they took the matter seriously when it first came up, and obviously there was a very serious concern that we can see in retrospect. and i would be particularly concerned about someone who visited an area like chechnya, if that's in fact what happened, especially in the light of the fact that chechny